Design of an Impeller Mounted Electrode Array

S. C. Murphy and T. A .York

SISP, School of Electrical & Electronic Engineering, University of Manchester, UK M60 1QD E-mail: s.murphy@student.manchester.ac.uk

ABSTRACT

The information content in Electrical Impedance Tomography (EIT) reconstructions is limited by the number of impedance measurements acquired for each image frame. This paper describes the design and construction of an electrode array mounted onto a rotating impeller used for mixing processes. Through combining the process compliant rotation of the electrodes with a dynamic measurement protocol, a substantial increase in the number of independent measurements is reported. The impeller’s orientation is monitored using a magnetic position sensor and communications are realised using wireless protocols. A pitch-blade impeller is built and fitted with four electrodes. The impeller has been accurately modelled and measurement simulations closely correspond to those acquired using the array. The apparatus was used to successfully visualize a test distribution to a consistent standard compared with a conventional EIT electrode array and strategy. Presently, the limiting factor to this approach is the necessary high measurement acquistion rates that restrict impeller velocities.

Keywords electrical impedance tomography, process mixing, impeller electrodes, internal electrodes